Release of bug could put NZ native species at risk

New Zealand’s native insects and
plants will be put at risk if a proposal to release a
predatory bug to protect tomato plants goes ahead, says
University of Auckland biosecurity lecturer Dr Margaret
Stanley.

New Zealand’s native insects and
plants will be put at risk if a proposal to release a
predatory bug to protect tomato plants goes ahead, says
University of Auckland biosecurity lecturer Dr Margaret
Stanley.

Industry body TomatoesNZ, which represents New
Zealand tomato growers, has applied to the Government’s
environmental regulator, the Environmental Protection
Authority, to import and release Macrolophus
pygmaeusas a biocontrol agent for the greenhouse
whitefly. Growers say controlling greenhouse whitefly by
introducing a biocontrol agent would lower the use of
chemical sprays and increase yields.

But in her submission
to the EPA, Dr Stanley says if Macrolophus
pygmaeus is introduced to New Zealand, there is a high
risk of damage to New Zealand’s unique flora and
fauna.

“There is a risk some New Zealand native species
will be lost if this application is approved or at the very
least there will be irreversible damage to plant and
invertebrate animal communities. While the industry’s
drive to reduce the use of chemical sprays is admirable, the
likely negative consequences for New Zealand are likely to
be worse than the current spray regime.”

Dr Stanley says
a number of aspects of TomatoesNZ’s application to the EPA
are of concern, including the assertion that the predatory
bug is a specialist whitefly predator.

“Given that it
also feeds on aphids, moth eggs, caterpillars, thrips and
spider mites this is clearly a generalist predator and the
implications of releasing such an organism needs to be
considered with great care. Best practice for biocontrol
around the world is to use highly specific biocontrol agents
to reduce risk.”

While tomato growers are seeking to
breed colonies of Macrolophus pygmaeus for release
into greenhouses, Dr Stanley says the bug will have many
opportunities to escape through open cooling vents. It has
established outside greenhouses in the UK and the risk of
the same thing happening here is high.

“The most
reliable climate modelling shows Macrolophus
pygmaeus would have optimal ecoclimate conditions to
establish in Northland, Auckland and the east coast of the
North Island, and ‘suitable’ conditions extend south to
Nelson.”

Macrolophus pygmaeus was released
illegally in New Zealand in 2007 but did not survive outside
greenhouses. Dr Stanley says the industry is using that to
support its case, but argues the bug was not released on a
scale comparable to what is now proposed and the illegal
release was also very localised.

“The illegal release in
2007 can’t be compared to what could happen under the new
plan which will see the bug released into greenhouses on a
much larger scale and over a far wider area,” Dr Stanley
says.

Comparing New Zealand to the UK, where M.
pygmaeus was introduced in 1991, was also
misleading.

“Unlike Europe, a high proportion of our
native invertebrates are found nowhere else in the world and
some of them have yet to be scientifically described so that
we don’t even know whether or not they are threatened or
to what degree they will be impacted by the introduction of
this new species,” Dr Stanley
says.

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